U.S. patent application number 14/948034 was filed with the patent office on 2016-12-01 for controlling apparatus and method for electric drive transmission of dual-motor electric vehicle.
The applicant listed for this patent is SAIC Motor Corporation Limited. Invention is credited to Jing Gu, Zhengmin Gu, Chengjie Ma, Xianjun Ye, Peng Zhang, Pengjun Zhang, Jun Zhu.
Application Number | 20160347320 14/948034 |
Document ID | / |
Family ID | 54770873 |
Filed Date | 2016-12-01 |
United States Patent
Application |
20160347320 |
Kind Code |
A1 |
Zhu; Jun ; et al. |
December 1, 2016 |
Controlling apparatus and method for electric drive transmission of
dual-motor electric vehicle
Abstract
A controlling apparatus and method for an electric drive
transmission used in a dual-motor electric vehicle are disclosed,
wherein when the second motor is in the zero torque state, the
synchronizer is shifted to a neutral position, the second motor the
required torque being kept to be zero; after shifted to the neutral
position, if the target gear position is the neutral position,
gearshifting is completed, an if the target gear position is not
the neutral position, speed control to the second motor is
conducted to adjust its speed towards a target speed; once the
second motor is adjusted to the target speed, the second motor is
subjected to zero torque control, the second motor the required
torque being zero; once the second motor comes into a zero torque
state, the synchronizer is shifted to a target gear position, the
required torque of the second motor being kept to be zero; once the
synchronizer is located in the target gear position, the required
torque of the second motor changes towards a target value at a
proper changing rate; once the second motor real torque and is
equal to or larger than target torque, gearshifting is judged as
completed. Loss in wheel driving torque caused by the second motor
in the whole gearshifting procedure is compensated by the first
motor, so that gearshifting without power interruption can be
achieved.
Inventors: |
Zhu; Jun; (Shanghai, CN)
; Ma; Chengjie; (Shanghai, CN) ; Gu; Zhengmin;
(Shanghai, CN) ; Ye; Xianjun; (Shanghai, CN)
; Zhang; Pengjun; (Shanghai, CN) ; Zhang;
Peng; (Shanghai, CN) ; Gu; Jing; (Shanghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAIC Motor Corporation Limited |
Shanghai |
|
CN |
|
|
Family ID: |
54770873 |
Appl. No.: |
14/948034 |
Filed: |
November 20, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 61/0403 20130101;
Y02T 10/64 20130101; Y02T 10/645 20130101; B60W 30/1882 20130101;
Y02T 10/646 20130101; B60W 2710/083 20130101; B60W 2510/081
20130101; B60W 2710/1005 20130101; B60L 2220/42 20130101; Y02T
10/7275 20130101; B60K 1/02 20130101; B60L 15/2054 20130101; B60W
2510/1005 20130101; B60W 2510/083 20130101; B60W 30/188 20130101;
B60W 30/19 20130101; B60W 10/08 20130101; B60W 2710/081 20130101;
Y02T 10/72 20130101; F16H 2061/0422 20130101; B60W 10/11 20130101;
B60W 2510/101 20130101 |
International
Class: |
B60W 30/188 20060101
B60W030/188; B60W 10/11 20060101 B60W010/11; B60W 10/08 20060101
B60W010/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 29, 2015 |
CN |
201510287526.7 |
Claims
1. A controlling apparatus for an electric drive transmission used
in a dual-motor electric vehicle, wherein the dual motors comprises
first and second motors, the electric drive transmission is coupled
with the first and second motors in a way that the first motor
outputs power with a single gear, and the second motor selectively
outputs power with two gears by means of a single synchronizer, and
the controlling apparatus is configured to receive information sent
from a vehicle controller, to control operations of the first and
second motors and the electric drive transmission, and to perform
gearshifting operation of the synchronizer by the steps of: (1) the
controlling apparatus starts to intervene in torque distribution of
the vehicle controller; (2) when the second motor is in a zero
torque state, the synchronizer is shifted to a neutral position,
and in this stage, the required torque of the second motor keeps to
be zero; (3) after the synchronizer is shifted to the neutral
position, if the target gear position is the neutral position, the
gearshifting procedure is completed, and if the target gear
position is not the neutral position, speed control to the second
motor is conducted to adjust its speed towards a target speed; (4)
once the speed of the second motor has been adjusted to the target
speed, the second motor is subjected to zero torque control, the
required torque of the second motor being zero; (5) once the second
motor comes into a zero torque state, the synchronizer starts to be
shifted to the target gear position, and in this stage, the
required torque of the second motor keeps to be zero; (6) once the
synchronizer is located in the target gear position, the required
torque of the second motor changes towards a target value at a
proper changing rate; (7) when the real torque of the second motor
and is equal to or larger than target torque, the gearshifting
procedure is judged as completed.
2. The controlling apparatus of claim 1, wherein in Step (1), the
required torque of the second motor changes towards zero torque at
a proper changing rate, and at the same time, the torque of the
first motor changes towards a target value of the required torque
of the first motor which is calculated based on a required torque
of the whole vehicle at wheel; and wherein when the second motor is
in the zero torque state, the first motor keeps its target value of
the required torque to support the power requirement of the whole
vehicle.
3. The controlling apparatus of claim 1, wherein in Step (6), the
target value of the required torque of the second motor is a
required torque that the vehicle controller distributed to the
second motor based on the operation mode of the transmission.
4. The controlling apparatus of claim 3, wherein the vehicle
controller performs optimization to working points of the first and
second motors with a synchronized transmission efficiency of the
first and second motors as the optimization objective, to determine
the required torques of the first and second motors.
5. The controlling apparatus of claim 1, wherein in Step (7), after
the gearshifting procedure is judged as completed, the controlling
apparatus ends its intervention in torque distribution of the
vehicle controller.
6. The controlling apparatus of claim 1, wherein the controlling
apparatus is configured to control the first and second motors and
the electric drive transmission so that they operate in the
operation modes of: a disconnect mode in which the synchronizer is
in its neutral position, and the first and second motors are both
in a standby state; a first-motor-only driving mode in which the
synchronizer is in the neutral position, the first motor is in a
torque control state conducted by the controlling apparatus, and
the second motor is in a standby state or in a speed control state
or a zero torque control state conducted by the controlling
apparatus; and a both-motors driving mode in which the synchronizer
is in a first-gear or second-gear position, the first motor is in a
torque control state conducted by the controlling apparatus, and
the second motor is in a standby state or in a speed control or a
torque control state conducted by the controlling apparatus.
7. The controlling apparatus of claim 6, wherein in the
first-motor-only driving mode, when there is no demand on shifting
the synchronizer to the first-gear or second-gear position from the
neutral position, the second motor operates in its standby state;
when the synchronizer is in a speed synchronization stage for
shifting towards the first-gear or second-gear position from the
neutral position, the second motor operates in a speed control
state; and when the synchronizer is in a stage from the time that
the speed synchronization for shifting towards the first-gear or
second-gear position from the neutral position is completed until
the completion of gearshifting, the second motor is in the zero
torque control state.
8. The controlling apparatus of claim 6, wherein in the both-motors
driving mode, the speed control of the second motor occurs in a
speed synchronization stage during the procedure of shifting the
synchronizer between the first-gear position and the second-gear
position.
9. The controlling apparatus of claim 6, wherein the controlling
apparatus is configured to conduct switching between operation
modes based on mode switching conditions Condition0 to Condition6
which are defined as: Condition0: when the system operates in a
power on state, unconditionally enters the disconnect mode;
Condition1: any one of the following subcondition (1), subcondition
(2) and subcondition (3) is met, and it is not in the gearshifting
procedure: subcondition (1)--the gearshifting lever is in R
position; subcondition (2)--the gearshifting lever is in N
position; subcondition (3)--the gearshifting lever is in D
position, and it is not beneficial for the second motor to
participate in driving in either the first gear or the second gear;
under condition Condition1, switching to first-motor-only driving
mode from the disconnect mode is to be conducted; Condition2: the
gearshifting lever is in P position; under condition Condition2,
switching to the disconnect mode from first-motor-only driving mode
is to be conducted; Condition3: the gearshifting lever is in D
position, and it is beneficial for the second motor to participate
in driving in either the first gear or the second gear, and it is
not in the gearshifting procedure; under condition Condition3,
switching to both-motors driving mode from the disconnect mode is
to be conducted; Condition4: the same as Condition2; under
condition Condition4, switching to the disconnect mode from
both-motors driving mode is to be conducted; Condition5: the same
as Condition3; under condition Condition5, switching to both-motors
driving mode from first-motor-only driving mode is to be conducted;
Condition6: the same as Condition1; under condition Condition6,
switching to first-motor-only driving mode from both-motors driving
mode is to be conducted.
10. The controlling apparatus of claim 6, wherein the controlling
apparatus is configured to judge the target gear position of the
synchronizer based on the operation modes, and to determine to
conduct gearshifting when one of conditions Switch0 to Switch6
defined below is met: Switch0: when the system operates in a power
on state, unconditionally enters the neutral state; Switch1: the
gearshifting lever is in D position, and it is beneficial for the
second motor to participate in driving in the first gear; under
condition Switch1, shifting to the first gear from the neutral
position is to be conducted; Switch2: either of the following
subcondition (1) and subcondition (2) is met: subcondition (1)--the
gearshifting lever is not in D position; subcondition (2)--the
gearshifting lever is in D position, and it is not beneficial for
the second motor to participate in driving in either the first gear
or the second gear; under condition Switch2, shifting to the
neutral position from first gear is to be conducted; Switch3: the
gearshifting lever is in D position, and it is beneficial for the
second motor to participate in driving in the second gear; under
condition Switch3, shifting to second gear from the neutral
position is to be conducted; Switch4: the same as Switch2; under
condition Switch4, shifting to the neutral position from second
gear is to be conducted; Switch5: the same as Switch3; under
condition Switch5, shifting to second gear from first gear is to be
conducted; Switch6: the same as Switch1; under condition Switch6,
shifting to first gear from second gear is to be conducted.
11. The controlling apparatus of claim 10, wherein in Step (5),
when the switching action of the synchronizer towards the target
gear position becomes overtime, the synchronizer is moved back to
the neutral position, and then the synchronizer is moved again
towards the target gear position; and when the total number of the
actions goes beyond a limited value, the synchronizer is prohibited
from entering that target gear position.
12. The controlling apparatus of claim 11, wherein the controlling
apparatus comprises: a first motor controller in communication with
the vehicle controller for controlling the operation of the first
motor; a second motor controller in communication with the vehicle
controller for controlling the operation of the second motor; a
gear shifting controller for controlling the selective action of
the synchronizer to shift the transmission gear for the second
motor; and a transmission controller in communication with the
vehicle controller and the gear shifting controller for determining
expected working points of the first and second motors, and for
controlling the first and second motor controllers via the vehicle
controller and controlling directly the gear shifting
controller.
13. A controlling method for an electric drive transmission used in
a dual-motor electric vehicle, comprising the operations related
with the controlling apparatus of claim 12.
Description
TECHNICAL FIELD
[0001] The disclosure relates to a controlling apparatus and method
for an electric drive transmission used in a dual-motor electric
vehicle.
BACKGROUND ART
[0002] In current pure electric vehicles, a transmission with two
or more gear ratios is generally used for meeting requirements on
dynamic performance at low speed and economics at high speed. When
a mechanical type automated manual transmission (AMT) configuration
is used in a gear shifting mechanism of a pure electric vehicle,
power interruption occurs during gearshifting, so driving sense is
not good. On the other hand, when an electric drive transmission is
used, it is not feasible to give consideration at the same time to
eliminating power interruption during gearshifting and optimizing
motor working points in a relatively large range.
SUMMARY OF THE DISCLOSURE
[0003] In view of state of the prior art, an object of the
disclosure is to provide an improved control strategy for an
electric drive transmission used in a dual-motor electric vehicle
so that no power interruption occurs during gearshifting, and at
the same time, it is possible to optimizing dual motor working
points in a relatively large range.
[0004] In order to achieve this object, according to one aspect of
the disclosure, there provides a controlling apparatus for an
electric drive transmission used in a dual-motor electric vehicle,
wherein the dual motors comprises first and second motors, the
electric drive transmission is coupled with the first and second
motors in a way that the first motor outputs power with a single
gear, and the second motor selectively outputs power with two gears
by means of a single synchronizer, and the controlling apparatus is
configured to receive information sent from a vehicle controller,
to control operations of the first and second motors and the
electric drive transmission, and to perform gearshifting operation
of the synchronizer by the steps of:
(1) the controlling apparatus starts to intervene in torque
distribution of the vehicle controller; (2) when the second motor
is in a zero torque state, the synchronizer is shifted to a neutral
position, and in this stage, the required torque of the second
motor keeps to be zero; (3) after the synchronizer is shifted to
the neutral position, if the target gear position is the neutral
position, the gearshifting procedure is completed, and if the
target gear position is not the neutral position, speed control to
the second motor is conducted to adjust its speed towards a target
speed; (4) once the speed of the second motor has been adjusted to
the target speed, the second motor is subjected to zero torque
control, the required torque of the second motor being zero; (5)
once the second motor comes into a zero torque state, the
synchronizer starts to be shifted to the target gear position, and
in this stage, the required torque of the second motor keeps to be
zero; (6) once the synchronizer is located in the target gear
position, the required torque of the second motor changes towards a
target value at a proper changing rate; (7) when the real torque of
the second motor and is equal to or larger than target torque, the
gearshifting procedure is judged as completed.
[0005] According to a possible embodiment of the disclosure, in
Step (1), the required torque of the second motor changes towards
zero torque at a proper changing rate, and at the same time, the
torque of the first motor changes towards a target value of the
required torque of the first motor which is calculated based on a
required torque of the whole vehicle at wheel; and when the second
motor is in the zero torque state, the first motor keeps its target
value of the required torque to support the power requirement of
the whole vehicle.
[0006] According to a possible embodiment of the disclosure, in
Step (6), the target value of the required torque of the second
motor is a required torque that the vehicle controller distributed
to the second motor based on the operation mode of the
transmission.
[0007] According to a possible embodiment of the disclosure, the
vehicle controller performs optimization to working points of the
first and second motors with a synchronized transmission efficiency
of the first and second motors as the optimization objective, to
determine the required torques of the first and second motors.
[0008] According to a possible embodiment of the disclosure, in
Step (7), after the gearshifting procedure is judged as completed,
the controlling apparatus ends its intervention in torque
distribution of the vehicle controller.
[0009] According to a possible embodiment of the disclosure, the
controlling apparatus is configured to control the first and second
motors and the electric drive transmission so that they operate in
the operation modes of:
a disconnect mode in which the synchronizer is in its neutral
position, and the first and second motors are both in a standby
state; a first-motor-only driving mode in which the synchronizer is
in the neutral position, the first motor is in a torque control
state conducted by the controlling apparatus, and the second motor
is in a standby state or in a speed control state or a zero torque
control state conducted by the controlling apparatus; and a
both-motors driving mode in which the synchronizer is in a
first-gear or second-gear position, the first motor is in a torque
control state conducted by the controlling apparatus, and the
second motor is in a standby state or in a speed control or a
torque control state conducted by the controlling apparatus.
[0010] According to a possible embodiment of the disclosure, in the
first-motor-only driving mode, when there is no demand on shifting
the synchronizer to the first-gear or second-gear position from the
neutral position, the second motor operates in its standby state;
when the synchronizer is in a speed synchronization stage for
shifting towards the first-gear or second-gear position from the
neutral position, the second motor operates in a speed control
state; and when the synchronizer is in a stage from the time that
the speed synchronization for shifting towards the first-gear or
second-gear position from the neutral position is completed until
the completion of gearshifting, the second motor is in the zero
torque control state.
[0011] According to a possible embodiment of the disclosure, in the
both-motors driving mode, the speed control of the second motor
occurs in a speed synchronization stage during the procedure of
shifting the synchronizer between the first-gear position and the
second-gear position.
[0012] According to a possible embodiment of the disclosure, the
controlling apparatus is configured to conduct switching between
operation modes based on mode switching conditions Condition0 to
Condition6 which are defined as:
Condition0: when the system operates in a power on state,
unconditionally enters the disconnect mode; Condition1: any one of
the following subcondition (1), subcondition (2) and subcondition
(3) is met, and it is not in the gearshifting procedure:
subcondition (1)--the gearshifting lever is in R position;
subcondition (2)--the gearshifting lever is in N position;
subcondition (3)--the gearshifting lever is in D position, and it
is not beneficial for the second motor to participate in driving in
either the first gear or the second gear; under condition
Condition1, switching to first-motor-only driving mode from the
disconnect mode is to be conducted; Condition2: the gearshifting
lever is in P position; under condition Condition2, switching to
the disconnect mode from first-motor-only driving mode is to be
conducted; Condition3: the gearshifting lever is in D position, and
it is beneficial for the second motor to participate in driving in
either the first gear or the second gear, and it is not in the
gearshifting procedure; under condition Condition3, switching to
both-motors driving mode from the disconnect mode is to be
conducted; Condition4: the same as Condition2; under condition
Condition4, switching to the disconnect mode from both-motors
driving mode is to be conducted; Condition5: the same as
Condition3; under condition Condition5, switching to both-motors
driving mode from first-motor-only driving mode is to be conducted;
Condition6: the same as Condition1; under condition Condition6,
switching to first-motor-only driving mode from both-motors driving
mode is to be conducted.
[0013] According to a possible embodiment of the disclosure, the
controlling apparatus is configured to judge the target gear
position of the synchronizer based on the operation modes, and to
determine to conduct gearshifting when one of conditions Switch0 to
Switch6 defined below is met:
Switch0: when the system operates in a power on state,
unconditionally enters the neutral state; Switch1: the gearshifting
lever is in D position, and it is beneficial for the second motor
to participate in driving in the first gear; under condition
Switch1, shifting to the first gear from the neutral position is to
be conducted; Switch2: either of the following subcondition (1) and
subcondition (2) is met: subcondition (1)--the gearshifting lever
is not in D position; subcondition (2)--the gearshifting lever is
in D position, and it is not beneficial for the second motor to
participate in driving in either the first gear or the second gear;
under condition Switch2, shifting to the neutral position from
first gear is to be conducted; Switch3: the gearshifting lever is
in D position, and it is beneficial for the second motor to
participate in driving in the second gear; under condition Switch3,
shifting to second gear from the neutral position is to be
conducted; Switch4: the same as Switch2; under condition Switch4,
shifting to the neutral position from second gear is to be
conducted; Switch5: the same as Switch3; under condition Switch5,
shifting to second gear from first gear is to be conducted;
Switch6: the same as Switch1; under condition Switch6, shifting to
first gear from second gear is to be conducted.
[0014] According to a possible embodiment of the disclosure, in
Step (5), when the switching action of the synchronizer towards the
target gear position becomes overtime, the synchronizer is moved
back to the neutral position, and then the synchronizer is moved
again towards the target gear position; and when the total number
of the actions goes beyond a limited value, the synchronizer is
prohibited from entering that target gear position.
[0015] According to a possible embodiment of the disclosure, the
controlling apparatus comprises:
a first motor controller in communication with the vehicle
controller for controlling the operation of the first motor; a
second motor controller in communication with the vehicle
controller for controlling the operation of the second motor; a
gear shifting controller for controlling the selective action of
the synchronizer to shift the transmission gear for the second
motor; and a transmission controller in communication with the
vehicle controller and the gear shifting controller for determining
expected working points of the first and second motors, and for
controlling the first and second motor controllers via the vehicle
controller and controlling directly the gear shifting
controller.
[0016] The disclosure in another aspect provides a controlling
method for an electric drive transmission used in a dual-motor
electric vehicle, the method comprising the operations described
above in relation to the controlling apparatus.
[0017] According to the disclosure, loss in wheel driving torque
caused by the second motor in the whole gearshifting procedure is
compensated by the first motor, so that gearshifting without power
interruption can be achieved. By means of the disclosure, power
outputs of the two driving motors and automatic gearshifting of the
corresponding electric drive transmission can be coordinately
controlled according to the power requirement of the whole vehicle
of the pure electric vehicle, and at the meantime, optimizing motor
working points in a relatively large range becomes possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic view of an electric drive transmission
and its controlling apparatus for a dual-motor electric vehicle
according to an embodiment of the disclosure.
[0019] FIG. 2 is a schematic view of an electric drive transmission
and its controlling apparatus for a dual-motor electric vehicle
according to another embodiment of the disclosure.
[0020] FIG. 3 is a flowchart of judging the operation modes of the
electric drive transmission conducted in the controlling apparatus
shown in FIGS. 1 and 2.
[0021] FIG. 4 is a flowchart of judging the target gear position of
a synchronizer in the controlling apparatus shown in FIGS. 1 and
2.
[0022] FIG. 5 is a flowchart of a gearshifting process of the
electric drive transmission.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] Some possible embodiments of the disclosure will be
described now.
[0024] The disclosure relates to a controlling apparatus and
corresponding controlling method for an electric drive transmission
used in a pure electric vehicle driven by dual motors. The electric
drive transmission allows one motor to output power via a single
gear transmission path, and the other motor to output power via two
gear transmission paths. FIGS. 1 and 2 show two embodiments of such
an electric drive transmission; it can be understood that the basic
concept of the disclosure is also applicable in controlling of any
electric drive transmission of a dual-motor electric vehicle that
meet the above requirements.
[0025] In the first embodiment shown in FIG. 1, an electric drive
transmission for a dual-motor electric vehicle comprises a first
motor 1 and a second motor 2, which are disposed opposite to each
other.
[0026] Output power of the first motor 1 is transmitted to an
intermediate shaft 8 with a single transmission ratio through a
first-motor drive gearwheel 5 mounted on a first driving shaft 3
and a first-motor driven gearwheel 9 mounted on the intermediate
shaft 8 and meshed with the first-motor drive gearwheel 5. Output
power of the second motor 2 can be selectively transmitted to the
intermediate shaft 8 either with a first transmission ratio or gear
ratio (also the single transmission ratio of the first motor 1)
through the first-motor drive gearwheel 5 and driven gearwheel 9,
or with a second transmission ratio through a second-motor
second-gear drive gearwheel 7 mounted around the second driving
shaft 4 and a second-motor second-gear driven gearwheel 10 mounted
on the intermediate shaft 8 and meshed with the second-motor
second-gear drive gearwheel 7. A synchronizer 6 mounted on the
second driving shaft 4 has a neutral position, a position engaged
with the first-motor drive gearwheel 5 and a position engaged with
the second-motor second-gear drive gearwheel 7. The power
transmitted to the intermediate shaft 8 is then transmitted to a
differential 13 through a main speed reduction pinion 11 and a main
speed reduction gearwheel 12 engaged with the main speed reduction
pinion 11. The main speed reduction pinion 11 and the main speed
reduction gearwheel 12 form a main speed reducer.
[0027] The configuration described above, from the first driving
shaft 3 and the second driving shaft 4 to the main speed reduction
pinion 11, form the electric drive transmission according to the
first embodiment, as indicated by double-dotted lines in FIG. 1.
The synchronizer 6 is the only synchronizer in the electric drive
transmission of the disclosure, for achieving the switching of the
transmission paths of the second motor 2. In this transmission, the
first motor 1 outputs power through a single power output path
having a single transmission ratio, and the second motor 2 can
output power through two power output paths with two gear ratios,
wherein the second motor 2 in the first gear shares the same power
output path with the first motor 1, and thus has a first
transmission ratio which is the same as the single transmission
ratio of the first motor 1, and in the second gear has a second
transmission ratio which is different from the single transmission
ratio or the first transmission ratio.
[0028] In the second embodiment shown in FIG. 2, an electric drive
transmission for a dual-motor electric vehicle comprises a first
motor 1 and a second motor 2. The first motor 1 drives the first
driving shaft 3 to rotate, and the second motor 2 drives the second
driving shaft 4 to rotate.
[0029] Output power of the first motor 1 is transmitted to an
intermediate shaft 8 with a single transmission ratio through a
first-motor drive gearwheel 5 mounted on the first driving shaft 3
and a first-motor driven gearwheel 9 mounted on the intermediate
shaft 8 and engaged with the first-motor drive gearwheel 5. Output
power of the second motor 2 can be selectively transmitted to the
intermediate shaft 8 either with a first transmission ratio or gear
ratio through a second-motor first-gear drive gearwheel 14 mounted
on the second driving shaft 4 and a second-motor first-gear driven
gearwheel 15 mounted around the intermediate shaft and meshed with
the second-motor first-gear drive gearwheel 14, or with a second
transmission ratio through a second-motor second-gear drive
gearwheel 7 mounted on the second driving shaft 4 and a
second-motor second-gear driven gearwheel 10 mounted around the
intermediate shaft 8 and meshed with the second-motor second-gear
drive gearwheel 7. A synchronizer 6 mounted on the intermediate
shaft 8 has a neutral position, a position engaged with the
second-motor first-gear driven gearwheel 15 and a position engaged
with the second-motor second-gear driven gearwheel 10. The power
transmitted to the intermediate shaft 8 is then transmitted to a
differential 13 through a main speed reduction pinion 11 and a main
speed reduction gearwheel 12 engaged with the main speed reduction
pinion 11. The main speed reduction pinion 11 and the main speed
reduction gearwheel 12 form a main speed reducer.
[0030] It can be understood that, as an alternative solution, the
synchronizer 6 may be provided on the second driving shaft 4, and
can be selectively engaged with the second-motor first-gear drive
gearwheel 14 and the second-motor second-gear drive gearwheel 7
which in this case are both mounted around the second driving shaft
4.
[0031] The configuration described above, from the first driving
shaft 3 and the second driving shaft 4 to the main speed reduction
pinion 11, form the electric drive transmission according to the
second embodiment, as indicated by double-dotted lines in FIG. 2.
The synchronizer 6 is the only synchronizer in the electric drive
transmission of the disclosure, for achieving the switching of the
transmission paths of the second motor 2. In this transmission, the
first motor 1 outputs power through a single power output path
having a single transmission ratio, and the second motor 2 can
output power through two power output paths with two gear ratios,
wherein the second motor 2 in the first gear has a first
transmission ratio or gear ratio, and in the second gear has a
second transmission ratio which is different from the first
transmission ratio. The first transmission ratio of the second
motor may be different from the single transmission ratio of the
first motor 1.
[0032] In addition, each of the electric drive transmissions
according to the first and second embodiments as described above
further comprises a controlling apparatus for controlling the
transmission, the controlling apparatus comprising a first motor
controller 20 for controlling the operation of the first motor 1, a
second motor controller 30 for controlling the operation of the
second motor 2, a gear shifting controller 40 for controlling the
selective shift action of the synchronizer 6 for achieving the
input of the power of the second motor 2 and gearshifting, a
transmission controller (TCU) 50 for determining expected working
points of the two motors, and sending corresponding instructions so
that the first motor controller 20, the second motor controller 30
and the gear shifting controller 40 perform corresponding control
operations, and a vehicle controller 100 for coordinatively
controlling the two motors and other vehicle functionalities.
[0033] In the embodiments shown in FIGS. 1 and 2, the first motor
controller 20 and the second motor controller 30 are in
communication with the vehicle controller 100. When gearshifting is
desired, the transmission controller 50 takes over the control
right of the vehicle controller, and transfers target instructions
on speed control and torque control of the second motor 2 and
control targets of the torque of the first motor 1, all calculated
by the transmission controller 50, to the first motor controller 20
and the second motor controller 30 via the vehicle controller 100.
The gear shifting controller 40 is configured as a subsystem of the
transmission controller 50, and is in communication with it.
[0034] A gearshifting procedure conducted in the transmission is
described below: (1) the transmission controller 50 sends a torque
control instruction to the second motor controller 30 via the
vehicle controller 100, with a target torque of zero to which the
torque should be changed from currently instructed torque at a
proper changing rate. At the same time, the transmission controller
50 sends a torque control instruction to the first motor controller
20 via the vehicle controller 100, with a target torque calculated
in the following way: subtracting the driving torque of the second
motor at wheel from the required torque of the whole vehicle at
wheel, and then the torque target of the first motor is calculated
out according to currently engaged gear. In other words, the effect
on the driving torque at wheel caused by the change in the torque
of the second motor which is necessary for gearshifting is
compensated by the first motor.
(2) When the second motor comes into a zero torque state, the
transmission controller 50 sends a zero torque control instruction
to the second motor controller 30 via the vehicle controller 100,
and keeps this instruction.
[0035] When the real torque of the second motor which is fed back
by the second motor controller 30 via the vehicle controller 100
approaches zero, the transmission controller 50 sends an
instruction on moving a gearshifting fork of the synchronizer or a
force applying instruction to the gear shifting controller 40, so
that gearshifting is performed.
[0036] If the target gear position is the neutral position,
gearshifting is completed after an engagement ring of the
synchronizer is moved back to the neutral position.
[0037] If the target gear position is not the neutral position,
once the engagement ring is moved back to the neutral position, the
transmission controller 50 sends a synchronization state
information to the gear shifting controller 40, with the target
position being the target gear position, and at the same time,
sends a target torque instruction to the first motor controller 20,
and sends a target speed to the second motor controller 30, so that
speed synchronization before and after the gearshifting of the
second motor can be achieved.
[0038] In this stage, a torque control instruction is sent to the
first motor controller 20 via the vehicle controller 100, and the
driving torque of the whole vehicle at wheel is completely supplied
by the first motor.
(3) Once the speed synchronization of the second motor is
completed, a zero torque control instruction is sent to the second
motor. After the second motor enters the zero torque state, the
transmission controller 50 sends an instruction on moving the
gearshifting fork or a force applying instruction to the gear
shifting controller 40, so that the gearshifting fork pushes the
engagement ring to be engaged with a gearing of the synchronizer
disposed at the target gear position. After the engagement ring is
engaged with the gearing disposed at the target gear position, the
transmission controller 50 sends a gear keeping instruction to the
gear shifting controller 40, and at the same time sends target
torque instructions to the first motor controller 20 and the second
motor controller 30 via the vehicle controller 100, until the real
torques of the first and second motors come to their normal levels,
or until the gearshifting is overtime. Then, gearshifting is
ended.
[0039] In the whole gearshifting procedure, under the coordinate
control of the transmission controller 50, not only the torque
requirement of the whole vehicle at wheel can be met in real time,
but also speed synchronization and gearshifting of the second motor
can be carried out.
[0040] Thus, smooth gearshifting without power interruption can be
achieved.
[0041] The above described controllers can exchange data their
between via a CAN network or other communication means.
[0042] The transmission controller 50 may be an individual
controller which is connected to and in communication with the
vehicle controller 100; alternatively, the transmission controller
50 may be a module in the vehicle controller 100 which is connected
to and in communication with other modules.
[0043] The gear shifting controller 40 may be provided with an
actuation mechanism for driving the synchronizer 6 to move. For
example, the actuation mechanism comprises a gearshifting motor, a
worm-gear mechanism and a gearshifting fork. The worm-gear
mechanism transforms the rotational movement of the gearshifting
motor into a linear movement of the gearshifting fork, and
transfers a gearshifting force of the gearshifting motor to the
gearshifting fork, and the gearshifting fork drives the engagement
ring of the synchronizer 6 to move to achieve gearshifting. It can
be understood that other mechanisms, instead of the worm-gear
mechanism, that can transform the rotational movement of the
gearshifting motor into the linear movement of the gearshifting
fork can also be used here.
[0044] The transmission controller 50 is configured for receiving
information sent from the vehicle controller, and determining a
torque intervention target of the two motors and a synchronizer
position target, to achieve the gearshifting function without power
interruption. In the electric drive transmission according to the
first and second embodiments, the first motor 1 which is directly
connected to the transmission path with the single transmission
ratio acts as a main motor which provides driving power
continuously during the running of the vehicle, and the second
motor 2 acts as an assistant motor which provides assistant or
individual driving when the required vehicle torque or power is
high or the first motor has a low efficiency now. In the upshifting
or downshifting action of the second motor 2, the first motor 1
continuously outputs power to prevent power interruption.
[0045] In the electric drive transmission according to the first
and second embodiments, the transmission controller 50 is
configured such that, when the vehicle is driven by the first motor
1, the second motor 2 may be selectively put into one of a neutral
state and the first gear and second gear states by means of the
synchronizer 6, so that the second motor 2 may intervene or not
intervene in the vehicle driving; further, when the vehicle is
driving by both motors, the synchronizer 6 may be shifted between
the first-gear and second-gear positions, for facilitating the
optimization of working points of the first motor 1 and of the
second motor 2. The vehicle controller 100 may perform optimization
to working points (speed and torque) of the first motor 1 and of
the second motor 2 with a predetermined optimization objective,
such as synchronized transmission efficiency.
[0046] A controlling method which is performed by the transmission
controller 50 for controlling the transmission will be described
now.
[0047] First, according to the electric drive transmission of the
disclosure, a combination of operation states of a power
transmission system formed by the first motor 1 (herebelow referred
to as TM1), the second motor 2 (herebelow referred to as TM2) and
the electric drive transmission and the engagement positions of the
synchronizer is listed in Table 1.
TABLE-US-00001 TABLE 1 Operation modes of the power transmission
Positions of the system: synchronizer: Motor states: Disconnect
Neutral position TM1 standby TM2 standby (being disconnected) T1
Neutral position TM1 torque TM2 standby or speed control or
(driving by TM1 only) control zero torque control T2 Beneficial
First-gear TM1 torque TM2 torque control or speed (driving by both
position control control motors) Second-gear TM1 torque TM2 torque
control or speed position control control
[0048] In addition, if the vehicle is equipped with a mechanical
air conditioner, a configuration in which an electromagnetic clutch
for the compressor of the air conditioner is connected to TM2 can
be used. During parking or low speed driving of the vehicle, the
synchronizer is controlled to be in the neutral position, so that
the requirement of the compressor of the air conditioner, which is
applied to the driving motor, at the lowest running speed of the
compressor can be met. In this way, the air conditioner can work
properly in the full speed range of the vehicle. During the
operation of the air conditioner, when and the synchronizer needs
to be shifted between its neutral position, the first-gear position
and the second-gear position, the electromagnetic clutch for the
compressor shall be disconnected at the beginning of gearshifting,
and it may judge whether the electromagnetic clutch for the
compressor shall be connected again after gearshifting is
ended.
[0049] According to the motor states and the synchronizer positions
listed in Table 1, the transmission controller 50 of the disclosure
judges the operation mode of the electric drive transmission, a
flowchart of this judgment being shown FIG. 3.
[0050] The electric drive transmission of the disclosure has three
operation modes: Disconnect (being disconnected), T1 (driving by
TM1 only) and T2 Beneficial (driving by both motors). Disconnect
means that the two driving motors are both in a standby state
(Standby). T1 means that only TM1 is working for driving, and it is
in a torque control (Torque Control) state, while TM2 operates in a
standby (Standby) or speed control (Speed Control) or zero torque
control state. In this operation mode, if there is no demand on
shifting the synchronizer to the first-gear or second-gear position
from the neutral position, TM2 operates in its standby state; when
the synchronizer is in a speed synchronization stage for shifting
towards the first-gear or second-gear position from the neutral
position, TM2 operates in a speed control state; and when the
synchronizer is in a stage from the time that the speed
synchronization for shifting towards the first-gear or second-gear
position from the neutral position is completed to the completion
of gearshifting, TM2 is in zero torque control state. T2 Beneficial
means that, when TM1 is working for driving (under torque control),
TM2 is also working for driving (under torque control or speed
control). In this operation mode, the speed control of TM2 occurs
in a speed synchronization stage when the synchronizer is shifted
between the first-gear position and the second-gear position.
[0051] Conditions of switching between operation modes of the power
transmission system can be judged based on the position (P, R, N,
D) of the gearshifting lever and according to whether it is
beneficial for TM2 participating in driving with first or second
gear, which is determined according to requirements of the vehicle
dynamic performance economics. Concrete judging logics will be
described now.
[0052] FIG. 3 shows the conditions for switching between the three
operation modes: Condition0 to Condition6, as described below.
Condition0: when the system operates in a power on state,
unconditionally enters the disconnect mode (Disconnect);
Condition1: any one of the following subcondition (1), subcondition
(2) and subcondition (3) is met, and it is not in the gearshifting
procedure: subcondition (1)--the gearshifting lever is in R
position; subcondition (2)--the gearshifting lever is in N
position; subcondition (3)--the gearshifting lever is in D
position, and it is not beneficial for TM2 to participate in
driving in either the first gear or the second gear. Condition2:
the gearshifting lever is in P position. Condition3: the
gearshifting lever is in D position, and it is beneficial for TM2
to participate in driving in either the first gear or the second
gear, and it is not in the gearshifting procedure. Condition4: the
same as Condition2. Condition5: the same as Condition3. Condition6:
the same as Condition1.
[0053] Under a certain operation mode, when any corresponding
condition of Condition0 to Condition6 is met, the transmission
controller conducts gearshifting operation.
[0054] In T1 operation mode, the power requirement of the whole
vehicle (the driving power requirement of the whole vehicle
depending on the pressed degree of the acceleration pedal of the
brake pedal, or the electric braking force required by the braking
energy regeneration system) is completely met by TM1. In T2
Beneficial operation mode, TM1 and TM2 in combination meet the
power requirement of the whole vehicle, and the transmission
controller may optimize working points of TM1 and TM2 according to
the efficiency characteristics of TM1 and TM2 to improve the
vehicle economics.
[0055] Further, according to the motor states and the synchronizer
positions listed in Table 1, the transmission controller judges the
target gear position of the synchronizer, a flowchart of this
judgment being shown FIG. 4.
[0056] The target gear positions controlled by the synchronizer
comprises three positions: Neutral (neutral position), Gear1
(first-gear position) and Gear2 (second-gear position). Switching
conditions between these positions are Switch0 to Switch6, as
described below.
Switch0: when system operates in a power on state, unconditionally
enters the neutral position state (Neutral). Switch1: the
gearshifting lever is in D position, and it is beneficial for TM2
to participate in driving in the first gear. Switch2: either of the
following subcondition (1) and subcondition (2) is met:
subcondition (1)--the gearshifting lever is not in D position;
subcondition (2)--the gearshifting lever is in D position, and it
is not beneficial for TM2 to participate in driving in either the
first gear or the second gear. Switch3: the gearshifting lever is
in D position, and it is beneficial for TM2 to participate in
driving in the second gear. Switch4: the same as Switch2. Switch5:
the same as Switch3. Switch6: the same as Switch1.
[0057] When a corresponding condition of Switch0 to Switch6 is met,
the transmission controller judges that gearshifting is
necessary.
[0058] A complete gearshifting process performed by the
transmission controller is shown in FIG. 5, the process comprising
steps for judging whether gearshifting is necessary (as described
above) and a gearshifting procedure that is concretely carried out
after it is judged that gearshifting is necessary.
[0059] For achieving during gearshifting without power
interruption, and for being responsive to the change of torque
requirement caused by the operation of the acceleration pedal, the
disclosure provide a gearshifting procedure as described below.
(1) The transmission controller starts to intervene in the torque
distribution of the vehicle controller. The required torque of TM2
is changed to the target value zero torque at a proper changing
rate, and at the same time, the required torque of TM1 is
calculated by:
[0060] The required torque of TM1=(the required torque of the whole
vehicle at wheel--the real torque of
TM2.times.i.sub.b0.times.i.sub.g)/(i.sub.a0.times.i.sub.g)
wherein i.sub.g is the speed ratio of the main speed reducer;
i.sub.b0 is the speed ratio of the gearwheels involved in current
gear of TM2; i.sub.a0 is the speed ratio of the gearwheels involved
in the gear of TM1. (2) When TM2 is in a zero torque state, the
synchronizer is shifted to a neutral position. In this stage, the
required torque of TM2 keeps to be zero, the required torque of TM1
is the required torque of the whole vehicle at
wheel/(i.sub.a0.times.i.sub.g). (3) After the synchronizer is moved
to the neutral position, if the target gear position is the neutral
position, gearshifting is completed; and if the target gear
position is not the neutral position, TM2 is subjected to speed
control until its speed is adjusted to the target speed, wherein
the target speed of TM2=the speed of the output shaft
.times.i.sub.b0r.times.i.sub.g, in which i.sub.b0r is the speed
ratio of the gearwheels involved in the target gear of TM2. The
required torque of TM1 is the required torque of the whole vehicle
at wheel/(i.sub.a0.times.i.sub.g). (4) Once the speed of TM2 is
adjusted to the target speed, TM2 is subjected to zero torque
control, the required torque of TM2 being zero, and the required
torque of TM1 being required torque of the whole vehicle at
wheel/(i.sub.a0.times.i.sub.g). (5) Once TM2 comes into a zero
torque state, the synchronizer starts to be moved towards the
target gear position. In this stage, the required torque of TM2
keeps to be zero, and the required torque of TM1 is the required
torque of the whole vehicle at wheel/(i.sub.a0.times.i.sub.g).
[0061] In the stage of moving the synchronizer towards a target
gear position, if the action of the synchronizer becomes overtime,
the synchronizer is moved back to the neutral position, and the
process goes back to Step (3). In the condition that the target
gear position is not the neutral position, the gearshifting actions
in above Steps (3)-(5) will be repeated, or the control states of
corresponding torque and speed will be maintained. A maximum number
of gearshifting actions "n" (calibratable) can be set for a
gearshifting procedure. If the number of gearshifting actions
exceeds "n" but gearshifting is still not success, then the
synchronizer is prohibited from entering this target gear
position.
(6) Once the synchronizer is located in the target gear position,
the required torque of TM2 is changed to a target value at a proper
changing rate, the target value being the required torque that the
vehicle controller distributed to TM2 on the basis of the operation
mode of the power transmission system, and the required torque of
TM1=(the required torque of the whole vehicle at wheel--the real
torque of
TM2.times.i.sub.b0.times.i.sub.g)/(i.sub.a0.times.i.sub.g). (7)
When the real torque of TM2 is equal to or larger than the target
torque, the gearshifting procedure is judged as completed, and the
transmission controller ends its intervention in the torque
distribution of the vehicle controller.
[0062] The gearshifting procedure performed by the transmission
controller of the disclosure relates to judgment of target gear
position, setting the time sequence for gearshifting, action of the
synchronizer, and calculation of target instruction for speed
control and torque control of TM2, and at the same time, TM1 is
given its torque control target, so the torque requirement of the
whole vehicle at wheel can be met, and smooth gearshifting without
power interruption can be achieved.
[0063] According to the disclosure, the electric drive transmission
for a dual-motor electric vehicle can be controlled for achieving
driving by a single motor, driving by two motors, and smooth
gearshifting during riving by two motors without power
interruption. By means of combination of various operation modes,
vehicle economics and dynamic performance are further optimized.
Further, the torque coordinative control in the gearshifting
procedure is characterized in that the loss in driving power of the
whole vehicle caused by gearshifting of one of the motors is
compensated by the other motor which is directly connected to the
main speed reducer, which results in a more direct and stable
torque coordinative control with respect to the traditional
gearshifting in which gearshifting is performed by clutch to clutch
actions. Thus, the gearshifting quality of the disclosure is higher
than the gearshifting in traditional transmissions.
[0064] While the disclosure has been described here with reference
to certain embodiments, the scope of the disclosure is not limited
to the illustrated and described details. Rather, these details can
be modified in various manners without departing from the basic
concept of the disclosure.
* * * * *